A device of the type referred to hereinbefore is known in the art from DE 35 40 472 C2. The splice cassette described in this patent publication is explained in more detail in DE 35 40 473 C2. In the device of the type referred to, the cassette box is adapted for receiving a splice cassette of a double-walled component. The splice cassette is formed of plastic and is provided with a winding body having a winding groove for winding the single and bundle wires of glass-fiber cables up. Such a device is, on one hand, complex with regard to the construction of the cassette box and of the splice cassette, and is not optimum with regard to the support of the single and bundle wires of glass-fiber cables in the winding groove of the winding body belonging to the splice cassette, and with regard to the protection from damage or breakage of the single or bundle wires, since the single and bundle wires are commonly wound up and can come under high tension when doing this.